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Published: September 15, 2006
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Article type: Index
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A1-A7
Published: September 15, 2006
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Naoki MORI, Syouhei KIYOSAKI, Akimaro KAWAHARA, Michio SADATOMI
Article type: Article
Session ID: 2622
Published: September 15, 2006
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Two-phase diversion cross-flow arising from the pressure difference between subchannels are our concern in this study. In order to refine the cross-flow model, we conducted adiabatic air-water experiments using a vertical multiple-channel with two subchannels simplifying a BWR fuel rod bundle. The data obtained were the axial variations of air and water flow rates and void fraction in each subchannel and pressure difference between the subchannels under a hydraulically non-equilibrium flow with the pressure difference. The above data have been used to validate our subchannel analysis code modified to be applicable to a counter-current cross-flow case.
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Hiroyuki KUDO, Shinji MATSUNAGA, Tatsuya HIGUCHI, Akimaro KAWAHARA, Mi ...
Article type: Article
Session ID: 2623
Published: September 15, 2006
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Diversion cross-flow is an unidirectional cross-flow in a non-equilibrium flow, and occurs due to the time-averaged pressure difference between the subchannels. In this paper, experiments and analysis of the diversion cross-flow between triangle tight lattice rod bundle subchannels are presented. In the experiment, flow rates of gas and liquid, the pressure difference between the subchannels and the void fraction in each subchannel were obtained. In the analysis, the flow rates of gas and liquid, the pressure difference and the void fraction were calculated with the present subchannel analysis code based on a two-fluid model. The calculated results agree reasonably well with the experimental results.
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Shintaro OBARA, Kenji YOSHIDA, Tadayoshi MATUMOTO, Isao KATAOKA
Article type: Article
Session ID: 2624
Published: September 15, 2006
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In this research, the practical correlation and flow regime model is proposed on the basis of heat transfer coefficient analyzed from boiling heat transfer experiment, under temperature control, using following experimental parameter: mass flux in upstream [kgm^<-2>s^<-1>] and sub-cooled temperature in upstream [K]. As the result, it is indicated that forced convective boiling heat transfer coefficient under high mass flux condition show higher value than that of pool boiling. Correlation for heat transfer coefficient and experimental value agree well in DNB region and is demonstrated adequacy and practicability. This flow regime model is presupposed as high concentration droplet flow. And it is also noted that the gravity and centrifugal force affect to the heat transfer coefficient in some experimental condition for horizontal straight or curve tube.
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Se-Young CHUN, Sung-Deok HONG, Noriyuki WATANABE, Hiroshige KIKURA, Ma ...
Article type: Article
Session ID: 2625
Published: September 15, 2006
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An experimental study of heat transfer characteristics near the critical pressure has been performed with a vertical 5x5 heater rod bundle cooled by Freon 134a fluid. The CHF has been measured in a range of the pressure of 3.20〜4.03MPa (the critical pressure of Freon 134a is 4.059MPa). The critical power decreases sharply with the system pressure near the critical pressure and shows a trend towards converging to zero as the pressure approaches the critical point. The CHF phenomenon near the critical pressure no longer leads to an inordinate increase in the heated wall temperature such as the case of the DNB at normal pressure conditions. The existence of a threshold pressure at which the CHF phenomenon disappears has been observed near the critical pressure.
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Kimitoshi YONEDA, Ryo MORITA
Article type: Article
Session ID: 2626
Published: September 15, 2006
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Flow visualization experiments and numerical calculations were conducted to investigate the flow characteristics at orifice downstream, with contraction ratio of 0.6, related to pipe wall thinning phenomena in power plant piping systems, especially for flow accelerated corrosion (FAC). Turbulent kinetic energy was found out to be a presumable factor to affect on FAC, since its profile trend nearly matched with that of pipe wall thinning data at actual plant piping. Reattachment points of flow separation, created at orifice downstream, will be, at the utmost, 2.5 times of diameter (2.5D) with plant piping system condition, although they gradually shift towards downstream with increase of Reynolds number. From this result, for pipe wall inspection region at orifice downstream, 3.0D would be conservative enough, which is the regulated value in the current pipe wall thinning management standard for power plants.
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Shoji GOTO, Shuichi OHMORI, Michitsugu MORI
Article type: Article
Session ID: 2628
Published: September 15, 2006
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The total space and weight of the feedwater heaters in Nuclear Power Plant (NPP) can be reduced by replacing low-pressure feedwater heaters with the high-efficiency Steam Injectors (SI). The SI works as a direct heat exchanger between feedwater from condensers and extracted steam from turbines. It can get higher pressure than supplied steam pressure. The maintenance cost is lower than that of the current feedwater heater because of its simplified system without movable parts. This paper describes the analysis of the heat balance and plant efficiency of this Innovative-Simplified NPP with high efficiency SI. The plant efficiencies of the Innovative-Simplified BWR with SI are compared with those of the 1100MWe-class BWR. The SI model is adapted into the heat balance simulator with a simple model. The results show the plant efficiencies of the Innovated-Simplified BWR with SI are almost equal to the original BWR.
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Shuichi OHMORI, Chikako IWAKI, Michitsugu MORI, Yutaka ASANUMA, Tadash ...
Article type: Article
Session ID: 2629
Published: September 15, 2006
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A steam injector (SI) is a passive jet pump without movable parts, able to drive water by supersonic steam jet, reaching a discharge pressure even higher than the supply steam pressure. Moreover the SI works as a high-performance direct-contact heat exchanger between steam and water. This provides SI with capability to serve also as a direct-contact feed-water heater that heats up feed-water by using extracted steam from the turbine. We have developed multi-stage SIs, which have high performance in wide operation range and can be used in parallel-operation to simplify the feed-water heating system of nuclear and thermal-power plants. In this study, we carried out endurance tests in order to verify the performance and endurance of the multi-stage SIs under operation during prolonged time period. The multi-stage SIs have undergone a global amount of 40 hours operation with steam and no performance degradation has been evidenced. According to the inspection of inner parts of SI, high endurance of the component was shown in continuous operation under the conditions similar to those for which it is designed.
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Chikako IWAKI, Shuichi OHMORI, Yutaka ASANUMA, Michitsugu MORI, Tadash ...
Article type: Article
Session ID: 2630
Published: September 15, 2006
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A steam injector (SI) is a passive jet pump with no movable parts, able to drive water by supersonic steam jet, reaching a discharge pressure even higher than the supply steam pressure. We have developed multi-stage SIs by using steam directly extracted from the turbine, which has high performance in wide operation range and can be used in parallel-operation to simplify feed-water heating system of nuclear and thermal-power plant. In this study, we carried out endurance test in order to verify the performance and resistance of the SI under operation during prolonged time period and deaerate performance. The SI has undergone a global amount of 40 hours operation with steam and no performance degradation has been evidenced. According to inspection of inner parts of SI, good performance as a deaerator and good resistance of the component was shown in continuous operation under conditions similar to those for which it is designed.
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Yutaka ABE, Chikako IWAKI, Tadashi NARABAYASHI, Michitsugu MORI, Shuic ...
Article type: Article
Session ID: 2631
Published: September 15, 2006
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Next-generation nuclear reactor systems have been under development aiming at simplified system and improvement of safety and credibility. One of the innovative technologies is the supersonic steam injector, which has been investigated as one of the most important component of the next-generation nuclear reactor. The steam injector has functions of a passive pump without large motor or turbo-machinery and a high efficiency heat exchanger. The performances of the supersonic steam injector as a pump and a heat exchanger are dependent on direct contact condensation phenomena between a supersonic steam and a sub-cooled water jet. In previous studies of the steam injector, there are studies about the operating characteristics of steam injector and about the direct contact condensation between static water pool and steam in atmosphere. However, there is a little study about the turbulent heat transfer and flow behavior under the great shear stress. The present study, visible transparent supersonic steam injector is used to obtain the axial pressure distributions in the supersonic steam injector, as well as high speed visual observation of water jet and steam interface. The experimental results of the interfacial flow behavior between steam and water jet are obtained. It is experimentally clarified that an entrainment exists on the water jet surface. It is also suggested that the condensation shock wave causes the rapid pressure increase.
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Yuhki TAKAHASHI, Yasuo KOIZUMI, Hiroyasu OHTAKE, Tohru MIYASHITA, Mich ...
Article type: Article
Session ID: 2632
Published: September 15, 2006
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Characteristics of thermal-hydraulic phenomena in the steam injector were examined. Two-types of a test section were used: a straight condensing section type and a taper condensing section type. In experiments, a water jet from a nozzle of 5mm diameter flowed into the condensing test section pipe concentrically. The radial and the axial distributions of velocity and temperature of the water jet were measured. Analyses by using the STAR-CD code were also performed. Experimental results implied that the steam condensing on the water jet brought momentum in the water jet to result in more effective radial transport of heat and momentum. The STAR-CD code analyses to allow the interface between the wall that simulated the steam flow part and the water flow to move, i.e. creating momentum in-flux at the water jet interface, provided better results to support the experimental results. To increase the interfacial friction had a minor effect on the radial velocity distribution in the tested range. The heat transport to the radial direction in the taper condensing section type was also quite strong.
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Kenji YOSHIDA, Isao KATAOKA, Shuich OHMORI, Michitsugu MORI
Article type: Article
Session ID: 2633
Published: September 15, 2006
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Experimental studies on turbulence structure and characteristics on wavy interface on liquid film flow in annular two-phase flow were carried out concerned with the injector. In the central steam jet injector, steam/water annular two-phase flow is formed in the mixing nozzle, which consists of nozzle, throat and diffuser part. To make an appropriate design for high-performance steam injector system, it is important to accumulate the fundamental data of the thermo-hydrodynamic characteristics of annular flow passing through the steam injector. In this study, the gas-phase turbulence structure and characteristics of the wavy interface on liquid film flow were experimentally investigated. The measurements for gas-phase turbulence were precisely performed by using the hot-wire anemometer, and made clear the velocity profiles and turbulent intensity in the injector nozzle. The measurements for liquid film thickness by the electrode needle method were also carried out to investigate the characteristics of wavy interface such as base film thickness and wave height.
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[in Japanese], Nobuatsu TANAKA, Masayuki SAKAI, Michitsugu MORI
Article type: Article
Session ID: 2634
Published: September 15, 2006
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CFD is expected to have a major role to play in optimizing the design of steam injector. However, it is very difficult to simulate hydraulic phenomena in the stream injector because it contains various kinds of problems such as complicated geometries, multiphase flow, free surface, phase change and turbulence. Therefore, for the purpose of numerically simulating thermal hydraulic phenomena in steam injector system, we adopt the advanced CFD techniques such as CIVA and T-CUP methods. In this paper, the analysis algorithm is briefly described. Then we simulate three-dimensional thermal hydraulic phenomena in some case of steam injectors with adopting temperature recover method as a phase change model. And we check adequacy of our code for simulatie Steam injectors.
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Noriyuki SHIRAKAWA, Seigo HOSODA, Masanori NAITOH, Emilio BAGLIETTO
Article type: Article
Session ID: 2635
Published: September 15, 2006
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The Nuclear Power Engineering Corporation (NUPEC) has developed a severe accident analysis code "SAMPSON". SAMPSON's distinguishing features include inter-connected hierarchical modules and mechanistic models covering a wide spectrum of scenarios ranging from normal operation to hypothetical severe accident events. Each module included in the SAMPSON also runs independently for analysis of specific phenomena assigned. SAMPSON has been applied to various problems, such as OECD ISP-45 and -46, severe accident phenomena in typical PWR and BWR plants, hydrogen detonation of Hamaoka-1 BWR plant, and so on. Through these analyses, however, some points to be improved have been specified and computing performance was found to become considerably deteriorated for real plant analyses compared with experimental analyses. Some examples of improvements of SAMPSON modules are shown in this paper.
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Yuichi KOIDE, Masaki NAKAGAWA, Naoki FUKUSHI, Hirokuni ISHIGAKI, Kazue ...
Article type: Article
Session ID: 2636
Published: September 15, 2006
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In case of strong earthquakes, control rods are set in gaps between fuel assemblies to scram nuclear reactors. In seismic design of nuclear reactors, predicting the behavior of control rod insertion during earthquakes is important for estimating the scrammability. We developed a numerical analysis model for the scrammability of boiling water reactor. This model consists mostly of beam elements and lumped mass elements. We compared our calculations with the results of experiments using our proposed model. With the results of our analysis, we came to the following conclusions. First, our proposed model can simulate the behavior of control rod insertion such as the time history of control rod velocity and contact drag. Also, our proposed model provides good agreement with scram time.
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Hisashi NINOKATA, Tsunayuki OKUMURA, Norio ATAKE
Article type: Article
Session ID: 2637
Published: September 15, 2006
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The direct numerical simulation (DNS) is applied to fully-developed turbulent flows in both eccentric annulus and triangular pin bundles of infinite array configuration. The DNS for flows with Re_τ=770 in an eccentric annulus suggests that local laminarization starts to prevail in the narrow gap region. The DNS is carried out for turbulent flows, with different friction Reynolds numbers up to Re_τ=1,400, in a bundle with the pitch-to-diameter ratio (P/D) equal to 1.2, and for flows with Re_τ=400 in bundles of different P/D, i.e., 1.2, 1.1 and 1.05. Discussions are made on the influences of the subchannel pin wall and the gap spacing onto the turbulence characteristics and onto the distributions of mean axial velocity, secondary flow and wall shear stress, and the local laminarization phenomena in the narrow gap region.
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Akira YAMAGUCHI, Satoru WADA, Takashi TAKATA
Article type: Article
Session ID: 2638
Published: September 15, 2006
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Safety analyses for nuclear reactors involve inherently various uncertainties. The uncertainties come from the input parameters, physical modeling, and numerical methods employed. In the present study, a stochastic analysis of the decay heat removal of a liquid metal reactor is performed. The output from the stochastic analysis is to obtain the tolerance limit and the confidence level of the computational output, and to identify the sensitive input parameters to the output. The tolerance limit and the confidence level are evaluated using order statistics technique for the computational results. The importance of the individual input parameters are estimated using variance of the conditional expectation. Furthermore, a methodology has been developed for evaluating dependencies among input parameters. It is found that the proposed methodology is effective for understanding the stochastic safety analysis and the results.
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Satoshi NISHIMURA, Yoshihisa Nishi, Nobuyuki UEDA, Izumi KINOSHITA
Article type: Article
Session ID: 2639
Published: September 15, 2006
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A conceptual design of 4S (Super-Safe, Small and Simple) is a sodium cooled fast reactor. In order to evaluate the RVACS (Reactor Vessel Auxiliary Cooling System) performance in 4S reactor (10MWe, pool-type) under the loss of RVACS stacks condition, a three-dimensional thermal-hydraulic analysis inside the reactor vessel was conducted by PHOENICS. A protected loss of heat sink accident is selected and simulated to evaluate the capability of RVACS to cool the plant safely under such an unusual condition. Analytical results show that the loss of one out of two outlet stacks has much effect on RVACS performance than that of one out of two inlet stacks. The hot plenum maximum temperature is below 480℃ even under the condition that both one inlet and one outlet stacks are lost. This result indicates that the safety criteria for the fuel element and the structure of the primary coolant boundary are satisfied enough.
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Minoru TAKAHASHI, NOVITRIAN, Yumi YAMADA, Abu Khalid Rivai, Shouji UC ...
Article type: Article
Session ID: 2640
Published: September 15, 2006
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Conceptual design and safety analysis were performed for Pb-Bi Cooled Direct Contact Boiling Water Fast Reactor (PBWFR). Steels were surface-treated using sputtering method with Al and SUS304 targets for compatibility with Pb-Bi. The steels were corrosion-resistant in Pb-Bi at 700℃. Pb-Bi-water direct contact boiling two-phase flow in PBWFR was simulated numerically and experimentally. Measured void fraction could be described by modified drift flux model.
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Yoshihisa NISHI, Tomohiro FURUKAWA, Norimi AOTO, Izumi KINOSHITA, Akih ...
Article type: Article
Session ID: 2642
Published: September 15, 2006
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The corrosion tests have been performed to some types of the ODS (oxide dispersion strengthened ferritic) steels with different chemical compositions of chromium and aluminum in the static pool of the lead-bismuth eutectic for up to 4000 hours. The lead-bismuth eutectic was kept the high temperature of 650℃, and the oxygen concentration was controlled. As the results, chromium effect on corrosion has not been observed, and good corrosion resistance by aluminum oxide formation on the surface has been obtained.
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Toru OBARA, Terumitsu MIURA, Hiroshi SEKIMOTO
Article type: Article
Session ID: 2643
Published: September 15, 2006
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Lead-Bismuth Eutectic has good characteristics as a coolant for fast reactors, but it has a problem of polonium production. Some fundamental experiments were performed to investigate the characteristics of evaporation and adhesion of polonium. In the evaporation experiment, direct contact experiment of neutron irradiated lead-bismuth and water were performed. The results showed there was no clear evidence that evaporation of polonium was increased remarkably by the direct contact. In the adhesion experiment, chemical form of evaporated polonium was discussed from the adhesion characteristics. By these experiments, some fundamental knowledge were obtained related to evaporation of polonium from lead-bismuth eutectic.
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Masakazu SHIRAKAWA, [in Japanese], [in Japanese]
Article type: Article
Session ID: 4301
Published: September 15, 2006
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This paper proposes an intelligent start-up schedule optimization system for a thermal power plant. This system consists of a dynamic simulation, a neural network, and an interactive multi-objective programming technique. The features of this system are as follows. (1) The start-up schedule can be optimized based on multi-objective evaluation and (2) the optimal start-up schedule can be determined with a reasonable computing time and calculation accuracy through interaction between human beings and computers.
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Michitaka IKEDA, Masaru SAITO, Yoshihiro KISHI, Hiromi SHIRAI, Hisao M ...
Article type: Article
Session ID: 4302
Published: September 15, 2006
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This paper describes development of reduction technology of unburned carbon concentration in fly ash during blended combustion of sub-bituminous coal with bituminous coal using a pulverized coal combustion test facility of CRIEPI. In this investigation, blended ratio of sub-bituminous coal means 30%. Then, moisture content of sub-bituminous coal is about 20% and fuel ratio of bituminous coal is about 1.5. When both primary air velocity and swirl vane angle of secondary and tertiary air are reduced, oxygen consumption progressed efficiently around the burner outlet. And by adaptation of air injection point and ratio for multi staged air, both NO_x concentration at the exit of furnace and unburned carbon concentration in fly ash are able to be reduced. Furthermore, when pulverized coal is concentrated at the exit of burner, oxygen consumption is improved still more. As a result, it is cleared that unburned carbon concentration in fly ash is reduced to 3% at 100ppm of NO_x concentration at the exit of furnace by optimizing burner structure, operation condition and multi staged air injection condition.
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Toshinobu KOTSUJI, Hirofumi TSUJI, Michitaka IKEDA, Hiromi SHIRAI
Article type: Article
Session ID: 4303
Published: September 15, 2006
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It is very important to control the coal ash properties for effective utilization of coal ash. The influence of combustion conditions (particle size of pulverized coal, two-stage combustion ratio) and coal properties (fuel ratio, acid ratio) on the coal ash properties (size, specific surface area, density and shape) were examined by use of a pulverized coal combustion test furnace. As the particle size of pulverized coal decreased, the particle size of coal ash is decreased. On the other hand, the density of coal ash is increased and the shape of ash particle approaches spherical. The shape of ash particle becomes nonspherical with the increase in the two-stage combustion ratio because of increase in unburned carbon concentration in fly ash. The size distribution of coal ash becomes wide with the decrease in the fuel ratio.
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Haeyang PAK, Noriyuki KOBAYASHI
Article type: Article
Session ID: 4304
Published: September 15, 2006
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An oxygen-blown pulverized coal burner for the utilization of various kinds of coal was newly proposed and developed. The combustion efficiency of 99.7% was achieved by the moderate swirl burner. The flame stabilization could not be realized by the strong swirl burner, and the contents of unburned carbon in ash were more than that of the moderate swirl burner experiment. The distribution of vorticity in the moderate swirling flow was equally proportioned even though the flow ratio was changed between 0.15 and 0.88. Additionally, the state of untidiness was observed near center part of the burner nozzle in the strong swirling flow. The close relationship between combustion efficiency and vorticity profiles was found by the flow analysis of PIV. The moderate swirl burner was suitable for designing the burner structure in the oxygen-brown pulverized coal combustion.
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Ryunosuke ITOKAZU, Toshihiko YAMADA, Shinji WATANABE, Masato TAMURA, T ...
Article type: Article
Session ID: 4305
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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Pulverized-coal combustion under oxygen and recycle flue gas (Oxy-fuel combustion) is expected to be one of the promising systems on CO_2 recovery from pulverized-coal fired power plant. The research and development on Oxy-fuel combustion technology had advanced under the Clean Coal Technology Program from 1992. It can be suggested through these studies that Oxy-fuel combustion system is the economical and effective systems for CO_2 recovery from the pulverized-coal fired power plant. Feasibility study has been now carried out toward the demonstration of Oxy-fuel. Combustion test of three kinds of Australian coal was carried out using the pilot-test facilities in order to confirm the flame stability and combustion characteristics in it. In this paper, we introduce the test results with both air and oxy-fuel combustion.
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Naomitsu HIRATSUKA, Shiro KAJITANI, Yoshio TAMURA
Article type: Article
Session ID: 4306
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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In Japan coal is an important energy resource in terms of energy security, stability in price and supply. However, coal emits more greenhouse gas than other fossil fuels. IGCC is a promising clean coal technology to harmonize the reduction of greenhouse gas and coal utilization. Japan has been working on development of a unique air-blown IGCC technology that realizes the highest net efficiency and environmental friendliness. Clean Coal Power R & D Co., Ltd. and 9 utilities, EPDC and CRIEPI started the 250MW IGCC demonstration project in 2001. The demonstration project consists of three periods ; plant design, construction, and test operation. Currently, the plant is under construction inside the Nakoso power station of Joban Joint Power Co., Ltd. in Iwaki City. Construction will be completed in August 2007, followed by a series of operation tests. This paper presents the outline of the demonstration plant and the latest status of the project.
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Saburo HARA, Kazuhiro KIDOGUCHI, Maromu OOTAKA, Hiroaki WATANABE
Article type: Article
Session ID: 4307
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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Our laboratory is developing "Supporting Tool to Optimize Design and Operation of Coal Gasifier" that integrates the experimental technique and the numerical analysis technology. To establish this tool, "3 T/D Coal Gasifier for Basic Research" that enable the achievement of wide range of gasification condition and the quantitative evaluation of the various phenomenon in gasifier, was designed and set up. A lot of special measurement equipment to clarify the discharge characteristic of molten slag and the ash adhesion characteristic to the gasifier wall have been introduced into this gasifier. From the gasification test results with Chinese coal, it was clarified to be able to evaluate the gasification performances in high accuracy.
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Hiroaki WATANABE, Saburo HARA, Kenichi TOKORO, Isamu WATANABE
Article type: Article
Session ID: 4308
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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A system which can automatically obtain online plant status data and calculate an optimal operating condition refering to gasification performance evaluation functions is suggested by the authors in this paper. Optimization calculations with non-linear programming are performed in the system for operating conditions of a entrained flow coal gasifer under three gasifier's loads. Constraint of temperature inside the gasifier, calorific value of prodcut gas and amount of recycled char, are imposed on each calculation. The temperature inside the gasifier reflects taking into account a discharge of molten slag from the gasifier. Calorific value of product gas is refered to specifications of gas turbine combustor. Amount of recycled char is restricted within the capacity of recycling system of the plant. Fluctuation of air ratio is also taken into account in the optimization calculation. Results show that improvement of gasifier performance can be done in each gasifier's load, such as 0.28MJ/m^3N increase in calorific value of product gas in 100% load and 0.43 MJ/m^3N increase in 80% load, though optimal condition in 70% load cannot be found. It is confirmed that the system is effective for the assessment of the gasifier's operating condition and performance.
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Yoshiaki MATSUZAWA, Toshiyuki SUDA, Guangwen XU, Takahiro MURAKAMI, To ...
Article type: Article
Session ID: 4309
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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This study is devoted to evaluating the performance and the process size of the pressurized dual fluidized bed gasification process that consists of a bubbling bed type of a steam gasifier and a riser type of a partial oxidizer. The sensitivity analysis was conducted by a process simulation to investigate the effect of process parameters of gasification and steam temperatures on the efficiency and the sand circulation flow rate. The result of calculation showed that the efficiency was higher than that of conventional gasifier. The kinetics model of coal gasification with the variables of temperature, steam partial pressure and particle size of coal was also formulated based on the labo-scale experiments. The process simulator and the kinetics model of gasification can decide the process condition and the size of the gasifier.
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Se-Min JEONG, Toru SATO
Article type: Article
Session ID: 4310
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The direct injection of CO_2 into the deep ocean is one of the feasible ways for the mitigation of the global warming. In the assessment process of it, the estimation of environmental impacts is strongly required, such as the change of CO_2 concentration and its spreading area. It is necessary to make CO_2 disperse as fast as possible and it is thought that injection with a pipe by a moving ship is effective for this purpose. To numerically investigate the time change of CO_2 concentration by turbulence diffusion in both small and meso-scales in the ocean, a moving and nesting grid technique was developed. To numerically generate a proper fluctuating flow field, a low-wavenumber forcing technique was adopted. The developed method was tested and validated by the numerical simulation of the ocean turbulent field. And, from the result of CO_2 dispersion simulation, it was found that the moving ship method reduces the biological impacts in a large extent, compared with fixed-point release.
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Yuichi ABE, Yutaka ABE, Izuo AYA, Kenji YAMANE
Article type: Article
Session ID: 4311
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The technology of the deep-ocean CO_2 storage is expected to directly mitigate the source of the global warming. At deep-ocean condition above 4.45MPa and below 283K, the CO_2 clathrate hydrate crystals are formed as membrane at the interface between the liquid-water and the liquid-CO_2. In the previous study, high peak in the strength of the hydrate membrane is observed just below the dissociation temperature. But for lack of the membrane thickness data in a variety of parameter conditions, there is no experimental information about the mechanism of this high peak of the strength. In the present study, the measurements of the membrane thickness are conducted by using the laser-light interference method. The hydrate membrane thickness is estimated to be about 7μm-11μm at 10MPa and 3℃-10℃.
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Yasuharu NAKAJIMA, Hideyuki SHIROTA, Ryuji KOJIMA, Kenji YAMANE, Izuo ...
Article type: Article
Session ID: 4312
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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Ocean storage of carbon dioxide (CO_2) is one of greenhouse gas control technologies. The authors have proposed a CO_2 sending method for ocean storage using a mixture of liquid CO_2 and dry ice, CO_2 slurry. Releasing experiments of CO_2 slurry using a high-pressure tank was carried out to observe the behavior of CO_2 slurry released in highly pressurized water. CO_2 slurry was prepared by melting of dry ice in a chamber at the triple point of CO_2, -56 degrees of Celsius. Descending of CO_2 slurry drops in water was observed. However, releasing of cold CO_2 slurry caused the formation of tubular ice at the releasing nozzle, which narrowed the flow of CO_2 slurry to form slurry drops with a diameter smaller than the nozzle hole. The result implies that the formation of tubular ice at the nozzle should be reduced to control the size of slurry drops.
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Satoshi SOMEYA, Masahiro NISHIO
Article type: Article
Session ID: 4313
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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It is studied about a new strategy for the CO_2 sequestration. In this method, CO_2 is injected into a seabed, sediments under the seabed. CO_2 hydrate is one of stable phase in environment of seabed. The injected CO_2 can form the hydrate in a diffusion process under the seabed, resulting in a roofed seal-layer. A large amount of liquid CO_2 will be kept under the seal layer. The present article reports about an experimental study of a CO_2 permeability through the sediments with CO_2 clathrate hydrate. The permeability was measured at about 3, 6℃ and at about 7, 10MPa with different amount of water in a system. It was clarified that the sealing ability of the hydrate-layer was not affected by temperature and pressure condition so much, and depended on the total amount of water in the artificial sediments.
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Tsukasa KUMAGAI, Hiroyuki SANGAWA, Takashi SASAKI
Article type: Article
Session ID: 4314
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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This paper outlines technologies of CCS to apply to a planned project. The process of CCS consists of separation of CO2 from sources discharging large amount of CO2, transport to a storage site, and long-term isolation from the atmosphere. CCS came to be recognized as one potential option among the portfolios of mitigation actions for the stabilization of atmospheric GHG concentrations. JGC has been conducting a feasibility study for a CCS project in Malaysia LNG Complex and developing a methodology for applying the CDM. Technologies for CCS projects of CO2 separated from natural gas would have been already verified through a few ongoing full-scale projects. The eligibility of CCS as a CDM project has been started to be discussed internationally and a methodology of CCS on applying CDM would be expected to be approved in 2008. The first CCS-CDM project might be started after validation based on the methodology.
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Shinji YAMAGUCHI, Kotaro Ohga, Masaji FUJIOKA, Masao NAKO
Article type: Article
Session ID: 4315
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The Japanese Ministry of Economy, Trade and Industry began, in 2002, a seven year project on CO_2 sequestration in coal seams, entitled as "Japan CO_2 Geosequestration in Coal Seams Project (JCOP)". The purpose of this project is to develop a series of processes that can extract the CO_2 discharged from thermal power plants and other large scale emitters, fix it within coal seams in a stable state, and in the process, recover methane as a clean energy source. This paper describes overview of the project and introduces recent CO_2 sequestration test results at the Ishikari coal filed test site. The results indicated the advantage of CO_2 sequestration in coal seams, that is, CO_2 was sequestrated and at the same time, the recovery of coalbed methane was enhanced.
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Koji YAMAMOTO, Kaori TAKAHASHI, Ryosuke AOYAGI
Article type: Article
Session ID: 4316
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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One of the biggest barriers to realize the CO_2 geological sequestration is the uncertainty over the safety and long-term stability of stored CO_2. Modelling-based risk assessment and monitoring techniques are ways to assure such issues on safety and stability. However, it is difficult to make a universal procedure of monitoring deployment scheme due to the complexity of geological formations and leakage mechanisms. Therefore, the reservoir type is categorized into three types, and three levels of monitoring scheme are proposed for different purpose of monitoring. The first level is a simple monitoring to detect the unexpected leakage based ondirect monitoring near wellbore and remote sensing methods. The second level is to monitor the underground CO_2 migration to find fluid migration pathways using geophysical methods. The third level is a quantitative evaluation of fluid migration volume with intensive geophysical monitoring including permanent sensors.
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Mitsuyuki YAMAZAKI, Tetsuya SUEKANE, Shuichiro HIRAI
Article type: Article
Session ID: 4317
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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We proposed a new monitoring framework of CO_2 geological storage, which consists of the NMR technique to monitor the concentration of CO_2 solved into pore water around the bore hole, the streaming potential technique to successively monitor CO_2 migration, and the time-lapse seismic technique. Enhancement in relaxation of NMR signal due to the dissolution of CO_2 into pore water has been demonstrated experimentally. We numerically investigated the monitoring of bore hole current induced by migration of CO_2 due to streaming potential effect.
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Tetsuya SUEKANE, Tomohisa NOBUSO, Shuichiro HIRAI
Article type: Article
Session ID: 4318
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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We discuss the amount of CO_2 stored by residual gas trapping and solubility trapping based on the experimental results. While the reservoir efficiency is reduced by about one third compared with physical trapping by caprock, the residual trapping and the solubility trapping is viable options for safety of geological storage of CO_2.
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Toshihiko TAKAHASHI, Kazunori WATANABE
Article type: Article
Session ID: 4335
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The present paper reports on bench-mark tests of Reynolds averaged Navier-Stokes (RANS) calculations of turbine blade heat transfer. Two sets of the bench-mark problems for the linear eddy-viscosity models with various modifications are solved by three dimensional steady-state calculation. The original models tested are the one-equation model by Spalart and Allmaras, the k-ε model and the k-ω model. One of the bench-mark problems, simulating a previous wind tunnel test, is prediction of local heat transfer coefficient on a stationary blade in a single cascade. Another one is estimation of local blade temperature by conjugate heat transfer calculation simulating an internal-cooling blade in a gas turbine. Computational results present that the k-ω model bounded by turbulence time scale and the shear stress transport (SST) model with the modified k production term reasonably simulate the measurements.
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Masakazu OBATA, Motoaki MORI
Article type: Article
Session ID: 4336
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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This paper presents the result of static pressure distribution measurements on the surfaces of endwall and rim-side wall of the nozzle ring in a low-speed axial flow turbine. equipped a rotating disc with pin blades. The measurements were performed under a constant disc cavity gap and a constant blade Reynolds number with a secondary fluid flow from the disc cavity for the location of stationary pin blades moving between one pitch of nozzle blades. The possibility of the main flow enrolment to the disc cavity was discussed through the static pressure distribution characteristics on the endwall and rim-side wall surfaces.
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Takuji TOMINAGA, Nobuyuki OSHIMA
Article type: Article
Session ID: 4337
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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To investigate turbulent combustion phenomena in a gas-turbine combustor, we conduct a numerical simulation of a partially premixed turbulent combustion in a practical combustor. Large-Eddy simulation and 2-scalar flamelet approach are coupled and applied to the unsteady turbulent combustion simulation in the combustor geometry for modeling turbulent and combustion reaction phenomena, and also their interactions. Based on the predicted results and some additional simulations, the dependency of predicted result on the Sub-Grid-Scale turbulent models are investigated. The important issues toward a numerical prediction system for designing combustor are pointed out.
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Akihiro WAKITA, Ken-ichi KANEKO, Yoshiharu TSUJIKAWA
Article type: Article
Session ID: 4338
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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This paper presents a study of the performance of spiral recuperator that consists of 5-layers. We compared experimental results of a single layer spiral recuperator with analytical one. Next, we analyzed 5-layer spiral recuperator. As a result, the temperature effectiveness of 0.57 and pressure loss coefficient of 3.8kPa in the high pressure air side can be obtained. On the contrary, a pressure loss of another side (exhaust gas side) become rather large.
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Koji TANAKA, Yoshiharu TSUJIKAWA, Ken-ichi KANEKO
Article type: Article
Session ID: 4339
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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Recently, the necessity of micro motive power has risen. Then, the Ultra Micro Gas Turbine (UMGT) is expected as the new power sources. Premixed-flame combustor of n-butane/air for 20W output UMGT was tested. The combustor size is 42mm in outer diameter and 19mm in inner diameter and the length L can be changed as follows ; 3.7mm, 6.7mm, 8.7mm. The influence on the flame shape, the limit of stability of combustion, the temperature distribution in the combustion chamber, and the gas temperature at the exit combustion when the length of combustion chamber and the equivalence ratio were examined. Although stable flame was not formed for L=3.7mm, stable flame can be formed for L=6.7mm, 8.7mm. The highest gas temperature at the exit combustor was 1080℃.
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Shuichi UMEZAWA
Article type: Article
Session ID: 4340
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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A new optical torque measurement method was applied to diagnosis of thermal efficiency of advanced combined cycle, i.e. ACC, plants. Since the ACC power plant comprises a steam turbine and a gas turbine and both of them are connected to the same generator, it is difficult to identify which turbine in the plant deteriorates the performance when the plant efficiency is reduced. The sensor measures axial distortion caused by power transmission by use of laser beams, small stainless steel reflectors having bar-code patterns, and a technique of signal processing featuring high frequency. The sensor was applied to the ACC plants of TOKYO ELECTRIC POWER COMPANY in order to analyze each steam turbine performance for selection of the plant that steam was extracted, following the success of inspection of the sensor reliability in ACC.
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Susumu NAKANO, Tadaharu KISHIBE, Satoshi DODO, Manabu YAGI, Kuniyoshi ...
Article type: Article
Session ID: 4341
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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A prototype machine for a next generation microturbine system applying a simplified humid air turbine system has been developing for its laboratory evaluation. Design target of electric output is 150kW, electrical efficiency is 35% LHV. A low NO_x combustor which applied a lean-lean zone combustion concept and water lubricated bearings were developed for the prototype machine, and power conversion system was integrated with water cooling Insulated Gate Bipolar Transistor. The main feature of this microturbine system is utilization of water for improvement of its electric output and electrical efficiency. Full speed test with no load, and rated load test without WAC and HAT were done successfully. 135kW electric output with the efficiency of more than 33% was obtained in the rated load test. Operation tests for WAC and HAT which were carried out under the condition of 63% load as a preliminary test showed significant effects on increase in electrical efficiency of 3.0 point% and electric output of 20%.
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